Feasibility and impact of a structured, exercise-based rehabilitation programme for intensive care survivors.

Our objective was to assess the impact of an outpatient physiotherapy-led rehabilitation programme on exercise capacity and anxiety and depression scores in a cohort of adult intensive care survivors. In a prospective study in a teaching hospital, 38 general intensive care survivors following hospital discharge underwent an established physiotherapy-led outpatient rehabilitation programme. The programme involved 2 hours of supervised exercise and education sessions each week and two unsupervised exercise sessions each week for 6 weeks. Assessments took place 1 week before and 1 week after completing the programme. Primary outcome measures were changes in exercise capacity measured using the 6-minute walk test (6MWT) and incremental shuttle walk test (ISWT). Secondary outcome measures were changes in anxiety and depression scores using the Hospital Anxiety and Depression Scale (HADS). Median distance covered in the 6MWT improved by 160 metres (p<0.001), and median distance covered in the ISWT also improved by 160 metres (p < 0.001). Significant improvement in anxiety (p = 0.001) and depression (p = 0.001) scores were also seen. Outpatient, physiotherapy-lead rehabilitation appears to improve both exercise capacity and anxiety and depression scores in a cohort of intensive care survivors. A similar programme should be tested in a randomised controlled trial.

Research for higher degrees.

This last article in the research series outlines the three commonest higher degrees available to the medical practitioner.

Tracheal gas insufflation apparatus. Performance of a novel phase-specific device.

Tracheal gas insufflation is a technique in which gas is injected intratracheally during positive pressure ventilation. The fresh gas rinses expired gas from the tracheal tube and anatomical dead space, aiding carbon dioxide elimination. This reduces ventilatory volume and pressure, helping to reduce ventilator-induced lung damage. Complications of tracheal gas insufflation include interference with ventilator function, tracheal damage and barotrauma. Expiratory washout is a variation of tracheal gas insufflation. We designed and constructed an original expiratory washout system and evaluated its safety and performance in lung and animal models. We found that expiratory limb and tracheal tube occlusion tests caused the device to disable itself at acceptable intratracheal pressures. We also demonstrated up to 31% reduction in tidal volume compared with conventional ventilation, supporting the possibility of using this device clinically to lessen volutrauma. We concluded that aspects of this design might alleviate many of the safety concerns of using tracheal gas insufflation.

The problem of informed consent in emergency medicine research.

The CRASH Trial (Corticosteroid Randomisation After Significant Head injury), which started in April 1999 hopes to answer the question of whether or not there is any benefit to giving high dose corticosteroids after significant head injuries. To do this patients are randomised to receive either the standard care for head injuries, as defined by the receiving hospital, or standard care plus a 48 hour infusion of corticosteroids. This is to be started within eight hours of injury, preferably as soon as possible. As all eligible patients will have a reduced level of consciousness informed consent has been deemed unnecessary. In this review the issue of consent in human experimentation is presented with a special emphasis on the problems faced in emergency medicine research, and the way these have been tackled.

Discovery of the intraosseous route for fluid administration.

One of the many problems in the resuscitation of the shocked patient is how to gain access to the circulation to provide fluids or drugs. Since the 1830s fluids have been administered intravenously. Intravenous access is not always possible in the very shocked patient. An alternative, used in the first world war, was the rectal route. This has rarely been used on a large scale since. Just before the outbreak of the second world war a chance discovery resulted in the development of intraosseous infusions of fluid and drugs. From its discovery it was used in adults and children. For many years it seemed to be ignored in adult resuscitation, but there are now signs of renewed interest in the technique. This brief review traces the discovery of the intraosseous route to put the current developments into a historical context.

Blood volume determination by the carbon monoxide method using a new delivery system: accuracy in critically ill humans and precision in an animal model.

OBJECTIVE: To evaluate accuracy and repeatability of blood volume determinations made by the carbon monoxide method, using a ventilator-driven administration system. DESIGN: Prospective within-patient comparison, using simultaneous measurements by two methods to determine accuracy. Prospective laboratory investigation in animals to estimate repeatability. SUBJECTS: For accuracy: Nineteen ventilated critically ill patients in a university hospital intensive care unit. For repeatability: Six anesthetized, mechanically ventilated normovolemic pigs because this is impossible to perform in humans. INTERVENTIONS: In the accuracy study, a small mass of carbon monoxide was administered via a closed breathing system and arterial blood samples were taken from existing cannulas. In the repeatability study, an intramuscular sedative was given, followed by an inhalational anesthetic induction and mechanical ventilation via a tracheal tube. Left axillary artery and external jugular vein cannulas were sited. Anesthesia was maintained using an intravenous infusion. Five sequential circulating hemoglobin and blood volume estimations were made using the carbon monoxide method. MEASUREMENTS AND MAIN RESULTS: The small carboxyhemoglobin increase produced by uptake of a small, known mass of carbon monoxide was used to estimate the circulating blood volume. Simultaneous measurement, using 51Cr-labeled red blood cells, was performed. Twenty measurements were made in 19 patients. The bias (mean difference between blood volume measurements by the two methods) was 397 mL (5.53 mL x kg(-1)) +/-415 mL (+/-5.95 mL x kg(-1)); the limits of agreement (mean difference +/-2 SD) were -433 mL and 1227 mL (-6.36 mL x kg(-1) and 17.42 mL x kg(-1)). Therefore, 95% of expected differences will lie between these limits. The mean blood volume was 75.8 mL x kg(-1) in the animals. The coefficient of variation of repeated estimates was 9.49%. Mean circulating hemoglobin mass was 7.31 mmol with a coefficient of variation of 10.18%. The mean hemoglobin concentration, by co-oximetry, was 5.014 mmol x L(-1), coefficient of variation, 2.99%. CONCLUSION: This arrangement is a potential bedside method of estimating blood volume and circulating hemoglobin mass. We have rendered the technique more acceptable clinically by creating a ventilator-driven administration system.

Modification of the cardiovascular response to hemorrhage by somatic afferent nerve stimulation with special reference to gut and skeletal muscle blood flow.

BACKGROUND: Tissue injury modifies heart rate and blood pressure responses to hemorrhage. The effect of concomitant injury on the hemorrhage-induced redistribution of cardiac output is much less clear. However, if injury elicits the visceral alerting response of the defense reaction, then a change in this redistribution of peripheral blood flow might be expected. If such a change compromised the gut circulation, then it might explain the deleterious effects of injury on the ability to withstand hemorrhage. METHODS: Immature pigs anesthetized with Saffan were bled 30% of blood volume with or without concomitant somatic afferent (brachial) nerve stimulation (to mimic injury). In addition to global cardiovascular and oxygen transport variables, blood flow was measured in the cranial mesenteric (gut) and right femoral (skeletal muscle) arteries after a 60-minute stabilization period after surgery, at the end of the 30-minute hemorrhage, and after a 30-minute shock period. RESULTS: Hemorrhage induced the expected cardiovascular and oxygen transport changes accompanied by a reduction in skeletal muscle blood flow and a 55% increase in skeletal muscle vascular resistance, but gut blood flow and vascular resistance were unchanged. However, in the presence of brachial nerve stimulation, the pattern of response to hemorrhage was modified, such that gut blood flow was now reduced and gut vascular resistance increased. CONCLUSION: The sparing of the gut circulation after hemorrhage was abolished in the presence of "injury." This finding is consistent with injury eliciting the defense reaction and may help explain the deleterious effects of injury on resistance to hypovolemia.

Systemic responses to trauma.

The systemic responses to trauma can be divided into cardiovascular, immunological, and metabolic. The cardiovascular responses are seen immediately after a traumatic insult. The pattern of response depends on whether the insult is mainly haemorrhagic, tissue damage, or a combination of the two. The response may be quite different for penetrating vascular trauma, compared with a crush injury to a limb. The immunological, or inflammatory, consequences of trauma usually become apparent several hours or days after the initial insult, although it is increasingly clear that they may be triggered by the very early cardiovascular changes. These have been implicated in the development of multiple organ failure. The metabolic responses are of greatest importance in the longer term: after successful resuscitation and after the definitive treatment of the patient's injuries. The metabolic responses need to be taken into account during the recovery from treatment and during the rehabilitation of the patient.